Apparatus for pollution contorl of furnace gases

ABSTRACT

A filter device is disclosed for removing of particulate material and reactive vapors from the exhaust gases from a furnace or the like. The device comprises a flow velocity reduction chamber for separating particles above a predetermined size. Particulate filter material is used to remove smaller particles from the exhaust stream. Chemicals may be added to the filter device, either into the chamber or into the particulate filter material. Means are provided for removing fouled particulate filter material.

United States Patent [1 1 Biasi 154] APPARATUS FOR POLLUTION CONTORL OFFURNACE GASES [76] Inventor: Charles P. Biasi, 74 Braman Road,

Waterford, Conn. 06385 [22] Filed: Nov. 23, 1970 [21] App]. No.: 91,763

[52] US. Cl. ..55/3l5, 55/432, 55/474, 55/512, 210/268, 210/270, 210/290[51] Int. Cl. ..B01d 23/16 [58] Field of Search....55/98, 99, 474, 432,512, 315; 210/268, 270, 274, 285, 288, 290; 263/196; 165/107; 209/490,491 493, 494, 495

[56] References Cited UNITED STATES PATENTS 793,745 7/1905 Shields..55/474 [4 1 Feb. 13,1973

1,766,221 1/1930 Lynch ..55/474 2,780,310 2/1957 Schaub ..2l0/2682,901,148 8/1959 Cunningham et al. ..222/l85 Primary ExaminerBemardNozick Azt0rneyColt0n and Stone ABSTRACT A filter device is disclosedfor removing of particulate material and reactive vapors from theexhaust gases from a furnace or the like. The device comprises a flowvelocity reduction chamber for separating particles above apredetermined size. Particulate filter material is used to removesmaller particles from the exhaust stream. Chemicals may be added to thefilter device, either into the chamber or into the particulate filtermaterial. Means are provided for removing fouled particulate filtermaterial.

10 Claims, 5 Drawing Figures SAND SAND TREATMENT CONVEYOR FACILITY 24 22PATENTEUFEB 13 I973 SHEET 10? 2 INVENTOR CHARLES P. De BIASIPAIENIEIJFEB 13 I973 SHEET 2 OF 2 INVENTOR CHARLES I? De BIASI APPARATUSFOR POLLUTION CONTORL OF FURNACE GASES BACKGROUND OF THE INVENTION Thepresently used devices for removing particulate material from furnacegases comprise a scrubber for spraying water through the gas. Thescrubber removes most of the particulates and reduces the temperature ofthe gases for introduction into an electrostatic precipitator. Althoughthis arrangement satisfactorily removes particulates, severe problemsoccur in removing collected materials from the precipitator and thendisposing of the scrub water.

The acquisition and disposal of scrub water is acute. Unless the scrubwater is treated and reused, the volume of scrub water required issubstantial generating high water bills and causing severe problems ofwater pollution. In addition, there is a problem of acidic or alkalinescrub water corroding or fouling the scrubber.

Proposals exist in the prior art for using particulate material filtersto remove contaminants from exhaust gases. Exemplary are the disclosuresin US. Pat. Nos. 793,745; 3,296,775; 3,505,008; and 3,410,055. The mostpertinent reference with respect to this invention is that of US. Pat.No. 793,745. In this disclosure, the particulate filter material isremoved more or less evenly from the entire filter bed. As will becomemore apparent hereinafter, the device of this invention removessubstantially only that filter material which becomes fouled mostreadily thereby minimizing the amount of filter material that must behandled.

SUMMARY OF THE INVENTION It is an object of this invention to provide anapparatus for pollution control of furnace gases utilizing particulatefilter material.

Another object of the invention is to provide a pollution control devicefor removing particulates and reactive vapors from exhaust streams usinga bed of particulate filter material including means for removing andreplenishing that portion of the filter bed which becomes fouled thequickest.

Another object of the invention is to provide an apparatus for removingparticulates and reactive material from exhaust streams using a bed ofparticulate filter material having exit means which may be adjusted tovary the quantity of material removed from the filter bed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross sectional view of anapparatus for pollution control of furnace gases constructed inaccordance with this invention;

FIG. 2 is a cross sectional view of the device of FIG. 1 takensubstantially along line 2-2 thereof as viewed in the directionindicated by the arrows;

FIG.-3 is a partial cross sectional view of the device of FIG. 2 takensubstantially .along line 3-3 thereof as viewed in the directionindicated by the arrows;

FIG. 4 is an enlarged cross sectional view of FIG. 3, takensubstantially along line 4-4 thereof as viewed in the directionindicated by the arrows; and

FIG. 5 is a cross sectional view, similar to FIG. 1, of anotherembodiment of this invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1and 2, there is shown a filter device 10 in accordance with thisinvention comprising as major components a flow velocity reductionchamber 12 provided by a roof 14 and a bed of particulate filtermaterial 16, means 18 for introducing particulate laden gas into thechamber 12, means 20 for removing fouled filter material, a filtermaterial treatment facility 22 and means 24 for conveying clean filtermaterial back to the device 10.

The roof 14 defines the top of the chamber 12 and comprises a conicalcap 26 supported by an annular ring 28 which is in turn supported by aplurality of columns 30. The columns 30 elevate the cap 26 above anunderlying ground surface or foundation 32. For purposes more fullyexplained hereinafter, the cap 26 is preferably steeper than the angleof repose of the filter material 16. Since the cap 26 is conical, theoverall shape of the filter device 10 is likewise conical although itshould be understood that other convenient shapes, for example squareand rectangular, are suitable for the device 10.

The filter material 16 may be of any suitable type such as sand. Thefilter material 16 has a predetermined angle of repose as shown inFIG. 1. The height of the ring 28 and the width of the chamber 12 arepreferably correlated so that the filter material 16 flowing under theroof 14 from opposite sides thereof substantially meets in the bottom ofthe chamber 12. It will accordingly be seen that the chamber 12 isdefined by the upwardly converging sides of the roof 14 and thedownwardly converging sides of the filter material 16.

The overall plan of operation of the filter device 10 should now beapparent. Fresh sand 16 is transported by the conveyor 24 to adjacentthe apex of the cap 26 and then dumped thereon. Since the cap 26 issteeper than the angle of repose of the sand 16, the sand 16 flowsdownwardly and away from a central vertical axis 34 passing through thechamber 12. As the sand 16 moves off the roof 14, it flows downwardlyand toward the central axis 34 into the configuration shown in FIGS. 1and 2. After a substantial amount of particulate laden gas passesthrough the chamber 12 and then through the sand 16, part of the sand 16is withdrawn through the removing means 20 for reconditioning at thetreatment facility 22.

Supporting the outer edge of the sand body 16 is a levee 36 which may bemade of any suitable material but which is illustrated as made ofgravel. The gravel levee 36 provides an additional outlet for gaspassing through the device 10 and can normally be constructed at minimumcost. The levee 36 has an interior edge 37 presenting a steeper anglethan the angle of repose a of the sand 16 to direct sand movement towardthe central axis 34.

An important part of this invention resides in the sand removing means20. The removing means 20 comprises gate means 38 for periodicallyremoving part of the sand 16 from adjacent the sides of the chamber 12and conveyor means 40 for transporting the sand 16 removed from thedevice 10 to the treatment facility 22. As shown best in FIGS. 1, 2 and4, the gate means 38 comprises downwardly converging sides 42 providingan opening 44 at the lowest point thereof. A

clamshell 46 or other suitable gate is provided to close the opening 46and suitable power means (not shown) are provided to manipulate theclamshell 46 either manually or in response to operating conditions ofthe device 10, such as the pressure existing in the chamber 12.

As seen most clearly in FIG. 1, the opening of the gate means 38 causesmovement of the sand 16 downwardly through the opening 44 followed bymovement of sand along a path indicated by the dashed arrow. It will beapparent that the opening of the gate means 38 removes the support forsand residing between the sides 48 of the chamber 12 and an imagineryline 50 parallel thereto. It will accordingly be seen that the means 20removes the particulate filter material 16 substantially only from thesides of the chamber 12. Since the filter material 16 in this region isthat which becomes fouled the quickest, it will be apparent that theonly sand actually being removed is that which actually carries asubstantial amount of particulates.

The clamshell 46 is closed, either upon command or automatically inresponse to operational parameters such as the pressure in the chamber12 or the mass of sand removed therefrom. When the clamshell 46 isclosed, movement of the sand 16 continues for a short period to restorethe size of the chamber 12 as shown in FIG. 1. It will accordingly beseen that the gate means 38 is disposed below the convergence of thechamber sides 48 and defines a path of particulate filter movementparallel to the converging sides 48 of the chamber 12.

The gate means 48 and the conveyor 40 may be housed in any suitablemanner. In FIGS. l-3, the gate means 38 is illustrated as positioned ina concrete well 52 having an upwardly inclined tunnel 54 extendingtherefrom to house the conveyor 40.

The filter device It) employs two filtering mechanisms to removeparticulates from the incoming gas stream. As is apparent from FIGS. 1and 2., the flow area of the chamber 12 substantially exceeds that ofthe gas introducing means 18 so that the flow velocity in the chamber 12is substantially less than that in the introducing means 18.Consequently, particles above a predetermined size, which are supportedby the gas velocity existing in the introducing means 18, are notsupported by the lower gas velocity in the chamber 12 whereupon theparticles fall out of suspension. As shown by the dash-dot arrows inFIG. 1, the gas in troducing means 18 defines a fiow path for particlesabove the predetermined size passing downwardly into the convergence ofthe chamber sides 48. Consequently, substantially all of the particlesabove this size accumulate in the convergence of the chamber sides 48.

The second filtering mechanism operative in the device is a screeningeffect of the smaller particles passing through the sand grains 16.Since sand is an efficient filter material, most of the smallerparticulates come to rest in sand 16 between the chamber side 48 and theimaginary line 50.

Referring nowto FIG. 5, there is shown another em bodiment of thisinvention illustrated as a filter device 110. For purposes of brevity,analogous reference characters are used on features common to theembodiment of FIGS. 1-4 with only the differences being specificallydiscussed.

There are two different features provided by the filter device which arenot shown in FIGS. 1-4. The gate means 138 is movable vertically in thewell 152 and includes flanges 1S6 extending thereinto and means (notshown) sealing the space between the well 152 and the flanges 156. Aforce applying means 158, such as a hydraulic cylinder, is provided toraise and lower the gate means 138. As will be apparent to those skilledin the art raising the gate means 138 decreases the quantity of the sand116 which is removed when the opening 144 is unobstructed, as by openingthe clamshell (not shown).

This feature presents several important advantages. It will beimmediately apparent that the gate means 138 may be elevated so that theconverging sides 142 are coplanar with the chamber sides 148. When theclamshell is open under these circumstances the only material passingthrough the opening 144 are particulates dropped out of the gas streamwhich fall into the convergence of the chamber sides 148.

In addition to removing only the particulates accumulating in theconvergence of the chamber sides 148, the gate means 138 may be loweredsequentially to remove decreasingly polluted segments of sand 116 fromadjacent the chamber sides of 148. In this regard, the dischargematerial may be analyzed to determine when the gate means 138 hasreached the elevation of the slope of clean sand, which would be thepoint at which the discharge of sand would be stopped and the gate means138 raised to the elevation where only fly ash could be discharged.

The remaining feature of this invention resides in means for chemicallyreacting gaseous pollutants introduced through the conduit means 118into a solid material which can be filtered by the sand 116. Toward thisend, there is provided means for introducing a chemically reactivematerial. The most common gaseous pollutant in the stack gases issulphur dioxide. It is known in the art of scrubbing gases to use thechemical reaction between sulphur dioxide and lime or magnesia toproduce calcium or magnesium sulphates. In this invention, limestone ordolomite is comminuted to produce particles sufficiently small so as notto fall out of suspension, because of velocity reduction, whenintroduced into the chamber 1 12. The crushed limestone or dolomite isinjected into the conduit means 160 and into the chamber 112. The sand116 adjacent the chamber sides 148 separates the crushed limestone ordolomite. The stack gases are introduced through the conduit means 118,the larger particles fall out into the convergence of the chamber sides148, the smaller particles accumulate in the sand 116 and the sulphurdioxide is reacted by the crushed limestone or dolomite accumulated bythe sand 116 to form calcium or magnesium sulphates.

An alternate arrangement for chemically reacting gaseous pollutantsintroduced through the conduit means 18, 118 into a solid material whichcan be filtered by the sand 16, 116 may be provided by disbursing areactive material in the sand. Thus the filter material may compriseintermixed sand and crushed limestone so that the limestone particleswill chemically react the sulphur dioxide to form calcium sulphate whichis filtered by the sand.

It will accordingly be seen that there is herein provided an improvedapparatus for pollution control of furnace gases.

1 claim: 1. A filter device comprising means defining a chamberincluding an elevated roof and means supporting granular filter materialexhibiting a predetermined angle of repose providing converging lowerside walls defined by the surface of the filter material which aredownwardly inclined in accordance with the angle of repose;

means defining a gas flow path into the chamber and then through thefilter material including means connected to the first mentioned meansfor introducing particulate laden gas into the chamber; and

means for removing filter material from the lower side walls andproviding a relatively stationary zone of filter material surroundingthe lower side walls including means for removing filter materialsubstantially only from the converging lower side walls of the filtermaterial and comprising outlet means disposed at the convergence of thelower side walls defining a passage for filter material.

2. The filter device of claim 1 further comprising means forgravitationally replenishing the filter material adjacent the chamberwherein the roof comprises upwardly converging sides defining a steeperangle than the angle of repose and means for delivering filter materialto the top of the roof.

3. The filter device of claim 2 wherein the chamber defined by theupwardly converging roof sides and the downwardly converging lower sidewalls is a large flow area compared to the flow area of the gasintroducing means, the chamber comprising a flow velocity reduction areafor separating particles from the gas above a predetermined size.

4. The filter device of claim 3 wherein the gas introducing meanscomprises means defining a flow path for particles above thepredetermined size including a segment passing downwardly toward theconvergence of the chamber side walls.

5. The filter device of claim 1 wherein the last mentioned meanscomprise gate means disposed adjacent the convergence of the filtermaterial defining a path of filter material removal parallel to theconverging lower side walls of the filter material.

6. The filter device of claim 5 wherein the outlet means comprisesdownwardly inclined convergent sides providing an opening at the lowerend thereof and means for selectively closing the opening.

7. The filter device of claim 6 further comprising means for raising andlowering the outlet means for altering the distance between the outletsides and the chamber side walls for altering the quantity of materialremoved from the device.

8. The filter device of claim 5 further comprising means for raising andlowering the gate means within the particulate material for altering thequantity of material removed from the device.

9. A filter device comprising means defining a chamber including a roofand means supporting granular filter material exhibiting a predeterminedangle of repose providing a flow velocity reduction chamber forseparating particles from. a gas above a predetermined size he chamberhaving a top defined by the roof and converging lower side walls,defined by the filter material, downwardly inclined in accordance withthe angle of repose; means defining a gas flow path into the chamber andthen through the filter material including means connected to thechamber for introducing particular laden gas into the chamber, the gasintroducing means having a smaller flow area than the chamber anddefining a path of uninterrupted falling movement for the particlesabove the predetermined size generally downwardly into the convergenceof the lower side walls; and means for removing particles accumulatingin the convergence of the lower side walls comprising gate meansdisposed at the chamber convergence 10. The filter device of claim 9wherein the two last mentioned means comprise gate means disposedadjacent the convergence of the sides defining a path of downwardparticle movement and a path of particulate filter material movementgenerally parallel to the converging sides and means for raising andlowering the gate means.

1. A filter device comprising means defining a chamber including anelevated roof and means supporting granular filter material exhibiting apredetermined angle of repose providing converging lower side wallsdefined by the surface of the filter material which are downwardlyinclined in accordance with the angle of repose; means defining a gasflow path into the chamber and then through the filter materialincluding means connected to the first mentioned means for introducingparticulate laden gas into the chamber; and means for removing filtermaterial from the lower side walls and providing a relatively stationaryzone of filter material surrounding the lower side walls including meansfor removing filter material substantially only from the converginglower side walls of the filter material and comprising outlet meansdisposed at the convergence of the lower side walls defining a passagefor filter material.
 1. A filter device comprising means defining achamber including an elevated roof and means supporting granular filtermaterial exhibiting a predetermined angle of repose providing converginglower side walls defined by the surface of the filter material which aredownwardly inclined in accordance with the angle of repose; meansdefining a gas flow path into the chamber and then through the filtermaterial including means connected to the first mentioned means forintroducing particulate laden gas into the chamber; and means forremoving filter material from the lower side walls and providing arelatively stationary zone of filter material surrounding the lower sidewalls including means for removing filter material substantially onlyfrom the converging lower side walls of the filter material andcomprising outlet means disposed at the convergence of the lower sidewalls defining a passage for filter material.
 2. The filter device ofclaim 1 further comprising means for gravitationally replenishing thefilter material adjacent the chamber wherein the roof comprises upwardlyconverging sides defining a steeper angle than the angle of repose andmeans for delivering filter material to the top of the roof.
 3. Thefilter device of claim 2 wherein the chamber defined by the upwardlyconverging roof sides and the downwardly converging lower side walls isa large flow area compared to the flow area of the gas introducingmeans, the chamber comprising a flow velocity reduction area forseparating particles from the gas above a predetermined size.
 4. Thefilter device of claim 3 wherein the gas introducing means comprisesmeans defining a flow path for particles above the predetermined sizeincluding a segment passing downwardly toward the convergence of thechamber side walls.
 5. The filter device of claim 1 wherein The lastmentioned means comprise gate means disposed adjacent the convergence ofthe filter material defining a path of filter material removal parallelto the converging lower side walls of the filter material.
 6. The filterdevice of claim 5 wherein the outlet means comprises downwardly inclinedconvergent sides providing an opening at the lower end thereof and meansfor selectively closing the opening.
 7. The filter device of claim 6further comprising means for raising and lowering the outlet means foraltering the distance between the outlet sides and the chamber sidewalls for altering the quantity of material removed from the device. 8.The filter device of claim 5 further comprising means for raising andlowering the gate means within the particulate material for altering thequantity of material removed from the device.
 9. A filter devicecomprising means defining a chamber including a roof and meanssupporting granular filter material exhibiting a predetermined angle ofrepose providing a flow velocity reduction chamber for separatingparticles from a gas above a predetermined size, the chamber having atop defined by the roof and converging lower side walls, defined by thefilter material, downwardly inclined in accordance with the angle ofrepose; means defining a gas flow path into the chamber and then throughthe filter material including means connected to the chamber forintroducing particular laden gas into the chamber, the gas introducingmeans having a smaller flow area than the chamber and defining a path ofuninterrupted falling movement for the particles above the predeterminedsize generally downwardly into the convergence of the lower side walls;and means for removing particles accumulating in the convergence of thelower side walls comprising gate means disposed at the chamberconvergence